Preparation of spectrographically nickel-free cobalt



Nov. 7, 1961 P. G. GRIMES 3,007,793

PREPARATION oF SPECTROGRAPHICALLY NICKEL-FREE COBALT Filed May 27, 1960 2 Sheets-Sheet 1 Nov. 7, 1961 P. G. GRlMEs 3,007,793

PREPARATION oF SPECTROGRAPHICALLY NICKEL-FREE COBALT Filed May 27, 1960 2 sheets-sheet 2 5mm/1129A I Da/buda 9.

United States iatent hhce 3,007,703 Patented Nov. 7, 1961 3,007,793 PREPARATIGN F SPECTRGRAPHICALLY NiCKEL-FREE CGBALT Patrick G. Grimes, Milwaukee, Wis., assigner to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. Filed May 27, 1960, Ser. No. 32,187 19 Claims. (Cl. 75-19) This present invention relates to a method of isolating speotrographically nickel-free cobalt from a cobalt-nickel nnxture.

The recovery and separation of nickel and cobalt from solution `by hydrometallurgical techniques has presented an exceptionally vexatious problem -through the years. The prior art has suggested several techniques which provided fairly good recovery but in nearly every instance, the selectivity of the techniques was very low.

Once such prior art method involves the use of hydrogen to selectively reduce nickel and cobalt compounds to the elements from ammonical solutions.

Another method involves the selective precipitation of nickel and cobalt carbonates from solution by the adjustment of the pI-I and the concentration of the am.- rnonium and carbonate ions.

These methods have achieved some measure of success in that the recovery of the metals from the solution is good. However, with no significant exception, all possess the disadvantage that their selectivity is very low.

The present invention is predicated upon my discovery that excellent recovery and selectivity can be obtained when nickel and cobalt are recovered from solution by the precipitation of their B-diketone chelates (hereinafter indicated as B-diketone") whereupon the differences in the volatility of the chelates from a solid state may be exploited to effect a selective separation of the metals and provide cobalt having a purity of better than 99.9 percent.

Accordingly, one of the primary objects of the present invention is the provision of a new method of isolating cobalt from a cobalt-nickel solution wherein both the recovery and the selectivity are of a high order and the cobalt isolated thereby is spectrographically nickel-free.

Another object of the present invention is to provide a novel method of selectively isolating cobalt from a cobaltnickel mixture in solution in which the elements are reduced to solid state chelates and thereafter separated selectively by the controlled application of heat.

Still another object of the present invention is to provide a method of isolating elemental cobalt having a purity of about 99.9 percent.

A further object of the present invention is to provide an improved method for isolating elemental cobalt from a cobalt-nickel solution in which the B-diketone reagent employed therewith is readily recovered by a hydrolysis reaction.

A still further object of the present invention is to provide a simple, expeditious, economically feasible method of segregating cobalt from a cobalt-nickel solution with chelating agents which may be readily and expeditiously reclaimed.

These and still further objects, as shall hereinafter appear, are fulfilled by the present invention in a remarkably unexpected manner which can be discerned from a careful consideration of the following detailed description, especially when read in conjunction with the attached drawing which schematically illustrates two embodiments of the present invention.

In the drawing:

FIG. l is a schematic flow sheet of a process embodying the present invention; and

FIG. 2 is a schematic flow sheet of another process embodying the present invention.

Referring to FIG. l, a cobalt-nickel mixture (usually from the mined ore since cobalt rarely occurs in nature without nickel and vice versa) is mixed with a suitable solvent, such for example, as HC1, H280.;t and the like, to provide a nickel-cobalt solution. In usual operations, this solution will be acidic since the most inexpensive of the available solvents for nickel and cobalt are acids.

To the nickel-cobalt solution is added an amount of B-diketone, such `as ZA-pentanedione or others as shall hereinafter be discussed, slightly in excess of a stoichiometric requirement for the metals present in the solution.

Gther metals which might accompany cobalt and nickel in the cobalt-nickel mixture when it is prepared from mined ore include iron, copper, manganese, aluminum andthe like. These metals, however, may be readily removed lby conventional techniques. The preliminary separation of foreign metals from a nickel-cobalt solution is already a Well known art and therefore needs no further elaboration here.

After the B-diketone is added to the solution, cobalt and nickel B-diketonates will immediately begin to precipitate from the solution. I have discovered, however,

that the rate of precipitation and the ultimate degree of reaction completion is greatly enhanced by the subsef quent addition of a compatible pH adjuster solution. Thus, to the solution is added a suficient amount of a pH adjuster, such as suitable bases including sodium hydroxide or potassium hydroxide and suitable `buffers including acetic acid-sodium acetate, to bring the pH of the solution to a value of between about 4 and 7.

Compatible as that term is herein used means that the pH adjuster solution does not enter into its own side reaction with the chelates. Thus hydroxides, such as ammonium hydroxide, which do have a tendency to react with chelates should not be used to adjust pH -at this stage of the process as they are not compatible As the pH of the solution approaches 7, for example, at about 4 the cobalt and nickel chelates (produced by the reaction of the cobalt-nickel mixture with the B-diketone) rapidly precipitate out of the solution in a substantially complete reaction.

As the pH is raised, the metal chelates precipitate. At pH levels higher than 7, the precipitate tends to become contaminated and it is therefore believed that the upper limit of the pH should be carefully controlled.

The chelate precipitates are crystalline and easily liltered. The color of the precipitate will vary from pink to gray to blue green as the concentration of cobalt decreased and the concentration of nickel increased. The precipitation of the metal chelates is quite complete.

The precipitate, which, as indicated, contains the chelates of cobalt and of nickel in a solid state, is removed from the solution using any suitable technique such, for example, as filtering, decantation, centriiication and the like. T-he precipitate is then passed through a drying zone (as represented by the dryer in FIG. 1) to remove any excess solvent or water that it may have carried from the solution.

The dried 'precipitate is then introduced into a heating zone (as represented by the snblimer in FIG. l) which is heated to a temperature of about C. but less than about C. at l atm. pressure. In this zone, hot vapors of an inert gas heated to temperatures of about 140 C. or greater, may be passed over and through the solid precipitate to transmit thermal energy to the precipitate. This thermal energy will sublime the cobalt chelate. The hot vapors will simultaneously remove any water of crystallization (or entrapped water) from the cobalt and nickel chelate crystals. It is, of course, understood that the sublimation temperature of the cobalt chelate can be lowered by the reduction of the operating pressure in the sublimer although this is not believed to be economically necessary.

Suitable inert 4gases for passage through the heating zone include nitrogen, argon, natural gas and other nonoxidizing volatile gases. Under the influence of the heat of the hot vapors in the heating zone, cobalt chelate will sublime from its solid state and pass oit' with the hot vapor flow. It is, of course, understood that these vapors may be eliminated, if desired, since they are used as a convenient carrier vehicle for heat and are in no way critical to the sublimation of the cobalt chelate, i.e., the cobalt chelate will sublime in the presence of other heat sources or even Without heat but not as efficiently. It is also noticed that if the nickel chelate is permitted to congregate too greatly on top of the precipitate, the volatilization of the cobalt chelate is somewhat retarded. This condition is readily corrected, however, by spreading the precipitate a little more thinly when introducing it into the sublimer or by slight mechanical agitation of the precipitate bed (eg. stirring or shaking) while it is heating in the sublimer.

The vapor passing from the sublimer may be passed through a suitable condenser and then passed as condensate into a hydrolyzing Zone; or the vapors may be introduced directly into a hydrolyzing zone. The hydrolyzing Zone is represented in FIG. 1 by a container of water.

It is found that the hydrolysis is greatly enhanced by heating the water to a boiling temperature and by providing the water with a pH of from about 2-8 by the addition of a suitable nonvolatile (at 100 C.) material, such for example, as sodium acetate-acetic acid buifer, and the like.

In the hydrolyzing bath thus formed, the cobalt chelate hydrolyzes to form B-diketone and a precipitate of cobalt hydroxide (some cobalt oxide may also form). Similar action takes place when the condensate resulting from condensation of the vapors is introduced into the water. The metal hydroxides produced and precipitated in the hydrolysis reaction are formed homogeneously. As a result, they are crystalline in appearance and are easily lilterable. The recovery of the hydroxides is good. After filtration, the ltrate may be used to dissolve and hydrolyze additional precipitate as it is passed from the heating zone.

The B-diketones can be removed from the hydrolysis solution by liquid-liquid extraction with Shellsol 72 (100% paraiiins having a boiling range of y170 C. to 185 C. sold by Shell Petroleum Company), or by azeotropic distillation with water, when 2,4-pentanedione is the specific B-diketone employed. In place of the Shellsol 72, other extraction liquids which are immiscible with water, have a boiling point in excess of 100 C., and an insolvency and chemical inertness relative to the metal chelates involved.

The B-diketone, reclaimed inthe above fashion, may be directly recycled back to the cobalt-nickel raw solution reaction.

In the case of the B-diiketone-water azeotrope, the azeotrope may be, if desired, -rst cooled whereupon two phases are formed; namely, one predominantly water and one predominantly B-diketone. The B-diketone rich phase may then be separated in a simple manner, as by decantation and then recycled back to the cobalt-nickel solution. Or as mentioned, the azeotrope may be directly fed back into the cobalt-nickel solution. Similarly, in the case of liquid-liquid extraction, the diketone rich phase may be reclaimed and then returned to the cobaltnickel raw solution reactor.

The cobalt hydroxide formed as the precipitant in the hydrolyzer is removed as by filtration and then passed to a reducing zone where, in the presence of a suitable reducing gas such, for example, as hydrogen, it is reduced to elemental cobalt. The elemental cobalt thus produced is found to be spectrographically nickel Ifree and better than 99.9 percent pure.

The residue in the sublimer, which is substantially nickel chelate with some cobalt chelate admixed therewith, is similarly removed from the sublimer or heatin-g zone and introduced into another hydrolyzer containing water which, as indicated, is preferably boiling and between pH 2-8.

In the hydrolyzer, as with the cobalt chelate, the nickel chelate (containing some cobalt chelate) is converted to a hydroxide (some oxide may be for-med) and the B-diketone is regenerated for addition to the raw cobalt-nickel solution.

The precipitate for the hydrolyzer is then passed to a reducing zone where the nickel and cobalt hydroxides are reduced to their elemental form. This product analyzes %-95% nickel and 5%-l0% cobalt.

Another method embodying the present invention is illustrated in FIG. 2 and comprises the introduction of a cobalt-nickel mixture (symbolized as Co/Ni) into a suitable reactor or vessel, solubilizing this mixture by the addition thereto of a suitable solvent such, for example, as sulfuric acid (or any of the others previously described), adding to the solubilized mixture a stoichiometric excess of a suitable B-diketone such, for example, as 2,4pentanedione (symbolized as HA), and then adjusting the final pH of the solution in this reactor to a value or" between 4 and 7 for the reasons described.

The solution, thus prepared, quickly reacts at room temperature to produce copious amounts of a precipitate containing the chelates of nickel and cobalt (symbolized as NiA2/COA2). The precipitate is readily removed from the solution by any suitable technique such as have been previously described.

The precipitate of nickel and cobalt chelates is then passed through a drying zone where excess water is removed therefrom.

The dried chelates are then introduced into another reactor ywhere they are mixed with benzene or a suitable substituted benzene such as chlorobenzene and the like.

In lieu of ben-zene, other solvents may be employed provided they are inert, i.e., will not react with the metal chelates, will dissolve relatively large quantities of the lmetal chelates, will permit the removal of water by distillation, either straight or azeotropically, and has a boiling point, at 1 atm., below about 130 C. or above about 200 C. (allowing 10 range with the significant boiling points in this process previously described).

This solvent functions, as does the sublimer previously discussed, to remove water of crystallization from and dehydrate the crystalline cobalt chelates dissolved therein. This is believed important because if the water of crystallization is not substantially removed from the cobalt chelate before volatilization, the chelate will, in part, hydrolyze instead of volatilizing and the eifectiveness of the method will be impaired.

The benzene-chelate slurry is next heated to a temperature at which the benzene-water azeotrope volatilizes (approximately 69 C.). Upon reaching about 69 C., the benzene-water azeotrope volatilizes out of the resulting solution and can be cooled and reprocessed in accordance with the well known benzene-water separation.

After the benzene-water azeotrope has been distilled from the benzene-chelate solution, the remaining solution (still containing some benzene) is passed into another reactor where it is mixed with a suitable high boiling temperature solvent such, for example, as dibutyl phthalate (symbolized as DBP), enzyl alcohol, decahydronaphthalene (decaline), tetrahydronaphthalene and the like.

The important attributes required for the solvent are that it will act as a heat transfer agent, will have sutilcient solubilizing power to make a concentrated solution of chelates, will have a boiling point suiciently high so that the vapor pressure of the solvent at the temperature of distillation of the cobalt chelate will be but a small portion of the total vapor pressure (to insure that the chelate will boil off instead of the solvent), that is, have a boiling point in excess of about 190 C., and will be inert to reaction with the metal chelates. Dibutyl phthalate provided quite satisfactory results, fulfilling all of these requirements, `as will hereinafter be used to exemplify the desired solvent. The chelates now reside in a benzene-dibutyl phthalate solution.

Because of the desire to maintain a relatively high concentration of the chelates in the solution, it is preferred that a minimal amount of the high boiling point solvent be added, i.e., the quantity of solvent to achieve saturation of the chelate present but little excess. A weight amount of the solvent is found to absorb an equal weight amount of the chelates.

This solution, which is somewhat cooled by the addition of the dibutyl phthalate, is reheated. As the solution reaches at a temperature of about 80-l-C., any benzene remaining in the solution will distill off. After the benzene has departed, the solution is continually heated until a temperature of 130 C.-14O C. is reached whereupon the cobalt chelate (COAZ) volatilizes and passes from the reactor. If desired, a stream of inert gases of the type previously described may again be employed to accelerate the withdrawal of the cobalt chelate from the reactor. Some dibutyl phthalate wil' also volatilize at this temperature although its primary function is to provide a solubilizing heat transfer media for heating the cobalt chelate and is not employed as a carrier agent.

Of course, as before reduced pressures may be ernployed which would enable the use of lower temperatures than indicated, the determination of which is well within the ordinary skills of the practicing chemist.

After the volatilization of the cobalt chelate is substantially complete, the reactor will contain essentially nickel chelate and some cobalt chelate in a dibutyl phthalate solution.

The volatilized cobalt chelate is next passed, either with or without prior condensation, into a hydrolyzer containing water, preferably boiling, whereupon the chelates hydrolyze to cobalt hydroxide (containing possibly some oxide) and B-diketone. The B-diketone may form, with the water, a B-diketone-water azeotrope as before. The B-diketone may be removed from the azeotrope in any suitable fashion, as by cooling, or it may be directly returned to the initial reactor for reuse. The dibutyl phthalate which was carried over by the cobalt chelate will remain in the hydrolyzer where it may decompose into other alcohols and acids, none of which have been found to have any significance in the hydrolysis reaction of the chelate.

Liquid-liquid extraction may also be employed to recapture the B-diketone as previously discussed.

It has already been noted that the rate of B-diketone recovery from hydrolyzer is enhanced by lowering the pH of the hydrolyzing solution. However, a practical limitation on this range occurs since a more acid solution will promote the polymerization of the B-diketone to an extent where the desired hydrolysis will be impaired. Satisfactory hydrolysis can `be obtained when this pH value lies between 2 and 8. The cobalt precipitate in the hydrolyzer (possibly some cobalt oxide) is next passed into a reducer where it is met by a suitable reducing gas, exemplified by hydrogen, and is readily converted to elemental cobalt. Spectrographic analysis of the cobalt product shows it to be 99.99 percent Co and contain approximately 0 percent nickel.

The residue remaining in reactor No. 3, after the cobalt chelate has been volatilized therefrom, is essentially nickel B-diketone with about 5 to l0 percent cobalt B- diketone (symbolized as NiA2/CoA2) in a dibutyl phthalate solution. This material is removed from the solution by cooling to room temperature whereupon the chelates precipitate. The addition of a small quantity of water to the cooled solution will enhance precipitation. The precipitate is then removed from the reactor as by ltering and passed to a hydrolyzer, operated in a like manner to the hydrolyzer previously described, where the chelates are decomposed to the metallic hydroxides (Ni(OH2)/Co(GH)2) and B-diketone. Again as before, the B-diketone wili tend to form an azeotrope with water and will flash distill from the hydrolyzer. The manner by which the B-diketone may be reclaimed has already been described.

The hydroxides (which may contain some oxides) are removed from the hydrolyzer and introduced into a suitable reducer where, upon engagement into a suitable reducing agent as exemplified by hydrogen, they are converted to elemental form. The element product, upon analysis, is found to contain to 95 percent Ni and 5 to l() percent Co.

In the practice of the present invention, it is found that 2,4-pentanedione is a very desirable B-diketone to use, both because of its effectiveness and because of its reiatively inexpensive price.

When 2,4-pentanedione is used, nickel and cobalt will be recovered from the solution, as described, through the precipitation of their respective 2,4-p-entanedionates. After separation of the chelates by volatilization in the manner described, the metal chelates are decomposed by hydrolysis into the metal hydroxides and the chelating agent, 2,4-pentanedione is regenerated.

The B-diketones exist in two tautomeric forms, viz., keto and enol.

t t t R-o-o-o-R n R-o cli-R' I H t H (kcto) (enol) In aqueous solution, at 25 C., about 2O percent of the 2,4-pentanedione is in Ithe enol form while 80 percent is in the keto form.

It is preferred, in the practice of the present invention that the B-diketone selected be one which R contains not over three carbon atoms since when R exceeds `this number of carbon atoms, the molecular weight of the B-diketone tends to reach a value which deters the volatility of the metal chelate and brings the temperature of volatility into relative coincidence with the decomposition temperature of the salt formed. To put it another way, it is desired in the practice of this invention to maintain a gap between the temperature of volatility of the metal chelate and its temeprature of decomposition.

lt has also been detected that when the B-diketone (considered in its keto form) has too great a diversity of symmetry, its volatility is likewise affected adversely. Thus, it should also be noted that the preferred practice of the present invention employs the B- diketone which is substantially symmetrical.

From the cost standpoint alone, it will be repeated, the preferred B--diketone is where both vR and R' are methyl groups which are, of course, 2,4-pentanedione acetylacetone) As previously discussed, it has been discovered that the nickel and cobalt B-diketonates, e.g.,2,4-pentanedionates, have the unusual property of being volatile at relatively low temperatures. rihus, in the solid state at l atm. pressure, the cobalt compound will begin to volatilize at a temperature of approximately C. while the nickel compound will not begin to appreciably volatilize until it reaches a temperature of about 196 C. This relaacercas tively large difference in volatility of the two compounds having almost .identical molecular weight is quite unexpected and no true explanation of this phenomenon is presently known. `l-t is, of course, understood that these temperature values may be altered by a variation of operating pressure. Important though is the maintenance of the relative difference in volatility points.

An alternative method of preparation of the mixed metal chelates will now be described.

The cobalt-nickel solution is basilied whereupon the cobalt and nickel precipiates as a mixed Ihydroxide. After filtration land drying, the mixed hydroxides are heated to reflux temperature with the reagent-solution, 2,4- pentanedione. In this reaction the Water azeotropically distills with the excess .2A-pentanedione thereby forcing the reaction to the right. After the reaction is complete, the nsolution is cooled whereupon the metal chelates will precipitate. This precipitate can then be handled in the manner previously described.

Another important aspect of the present invention which merits repetition occurs after the separation of the cobalt and nickel chelates, regardless of whether volatilization or sublimation is employed, viz., l have discovered that the reagent 2,4-pentanedione, can be recovered from 'the compounds by hydrolysis, In this process the metal constituent is converted to the hydroxide and/ or oxide.

The overall hydrolysis reaction is:

and is independent of pl-l. However, it is noted that the equilibrium lies to the left at 25 C. The reaction can be driven to the right by removing the ZA--pentanedione as `it is formed. This can be achieved, as previously described, by distilling olf the 2,4-pentanedious-water azeotrope. The metal chelate also dissociates in solution `according to the reactions This dissociation reaction is pl-l dependent, that is the lower the pH, the greater the dissociation and the larger the concentration of the undissociated ZA-pentanedione. Since the rate of removal of 2,4-pentanedione by distillation is proportional to `its concentration, a lower pH will create ta more rapid hydrolysis. However, the polymerization of 2,4-pentanedione, which is proportional to hydrogen ion concentration (places a lower limit on the pH range available for hydrolysis. It is, therefore, preferred that this pH be maintained between about 2 and 8.

The hydrolysis of cobalt `and nickel 2,4-pentanedionates has =been studied a-t various pH values. :Acetate buers were saturated with the metal chelates lat 100 C. and the 2,4-pentanedione that formed was azeotropically distilled with Water. The solubility of the metal chelates is found to -be directly proportional to the pH. Both chelates were soluble to approximately the same extent at this temperature (90 g./l., pH 4.0).

70 g./l., pH 4.6 40 g./l., pH 5.2 30 g./l., pH 6.0 9 g./l., pH 7.2

The 2,4-pentanedione are very nearly quantitively recoverable -by fractional distillation if sufficient time is allowed for the distillation. Recoveries of 93 to 98 percent were obtained in 1.5 hours. Seven hours were necessary to quantitive recovery.

An alternate method of hydrolysis at higher temperatures has also been attempted. Here the metal chelates are dissolved in relatively high boiling inert organic solvents. After the solutions have been heated to 149 C. to C., steam or water is introduced. The hydrolysis reaction of the dissolved metal chelates with water in this case produced 2,4-pentanedione and metal oxides. The oxides are formed homogeneously and are easily lterable crystalline compounds. Solvents which are found to give satisfactory results include decaline, 1,2,3,4 tetrahydronaphthalene, xylene, Shellsol 72 (100 percent paraflin boiling range C. to 185 C.) and 1,2,4 trichlorobenzene.

Thus a process for preparing spectrographically nickel-free cobalt from a cobalt-nickel mixture including the reclamation of the B-diketone reagent by hydrolysis has been described which fulliills all the aforestated objections in a remarkably unexpected fashion and advances the art to which it pertains to a significant degree.

It is, of course, understood that the foregoing description of certain embodiments and applications of the present invention are presented herein to convey an appreciation of the concepts herein involved and they are not intended necessarily as limitations thereupon; it being fully expected that these teachings may readily suggest to one skilled in the art other obvious variations, modifications, substitutions and applications of the present invention, all of which are yintended embraced within the spirit of this disclosure especially as it is deined by the claims appended hereto.

Having now particularly described and ascertained the nature of my said invention and the manner in which it is to be performed, l declare that what I claim is:

1. The method of isolating spectrographically nickelfree cobalt from a raw solution containing nickel and cobalt comprising: introducing an operable B-diketone into said solution and subsequent thereto, a pH adjuster to bring the pH of said solution to a value of from about 4 to `about 7 to precipitate nickel and cobalt as cobalt and nickel B-diketonates; separating said B-diketonate precipitate from said solution; removing surplus liquid from said precipitate; heating said precipitate to a temperature of at least about 140 C. to volatilize said cobaltB-diketonate without volatilizing said nickel B- diketonate; collecting said volatilized cobalt B-diketonate; and converting said volatiiized cobalt B-diketonate to elemental cobalt.

2. The method of claim 1 in which said volatilized cobalt B-diketonate is converted to elemental cobalt by hydrolizing said cobalt B-diketonate to cobalt hydroxide and reducing said cobalt hydroxide `to elemental cobalt.

3. The method of claim 1 in which the B-diketone has the keto form of OHO ll Il R- -tll-o-R' 111 where: R its a hydrocarbon radical selected from the group consisting of CH3, C2i-I5 and Cgi-i7 and R is a hydrocarbon radical selected from the group consisting Of CH3, C2H5 and C3Hr1.

4. The method of claim 2 in which said hydrolizing produces a B-diketone which can be substantially completely reclaimed, and reintroducing said reclaimed B- diketone into -said raw solution.

5. A method of claim 3 in which said B-diketone is substantially symmetrical.

6. The method of claim 3 in which said B-diketone is 2,4-pentanedione.

7. A method of selectively isolating the metallic elements nickel and cobalt via the formation of said elements into metal chelates with a B-diketone type chelating agent including the hydrolysis of said metal chelates in orgam'c solvents by mixture with water.

8. The method of isolating spectrographically nickelfree cobalt from a raw solution containing nickel and cobalt comprising: introducing a B-diketone into said solution; adjusting the pH of said solution to a value of between 4 and 7 to precipitate said nickel and cobalt as cobalt and nickel B-diketonates; separating said B-diketonate precipitate from said solution; removing surplus liquid from said precipitate to provide substantially dry precipitate; passing said dry precipitate into a heating zone heated to a temperature at least the equivalent of 140 C. at 1 atm. and not over the equivalent of 190 C. at 1 atm. while passing a flow of inert vapors through said zone over and through said dry precipitate whereupon said cobalt B-diketonate is volatilized from said precipitate and carried from said Zone with said vapors; passing said cobalt B-diketonate-containing-vapors into a hydrolysis zone of boiling water whereupon said cobalt B-diketonate hydrolyzes to B-diketone and a residuum cobalt compound containing essentially cobalt hydroxide, said B-diketone reacting with said water to `form a volatile azeotrope therewith; passing said cobalt compound from said hydrolysis zone into a reducing zone having a reducing gas passing ltherethrough to reduce said cobalt compound into spectrographically nickel-free elemental cobalt.

9. The method of claim 8 in which the B-diketone is substantially symmetrical and has the keto form of:

H o -Ml-Rf where: R is a hydrocarbon radical selected from the group consisting of CH3, C2H5 and C3H7 and R is a hydrocarbon radical selected from the group consisting Of CH3, C2H5 and C3H7- 10. The method of claim 9 in which the B-diketone is 2,4-pentanedione.

11. The method of isolating spectrographically nickelfree cobalt from a nickel-cobalt mixture comprising forming a solution containing the nickel-cobalt mixture and a chelating agent of the B-diketone type; adjusting the pH of said solution to a value of from 4 to 7 to precipitate nickel and cobalt chelates therein; removing said chelates from said solution; drying said chelates; mixing said dry cheltates with benzene; heating said mixture to dissolve said chelates and Volatilize a benzene-water azeotrope therefrom; mixing with said solution a high boiling point solvent selected from the group consisting of dibutyl phthalate, benzylalcohol, decahydronaphtbalene (decaline) and tetrahydronaphthalene; heating said mixed solution to a temperature of at least 130 C. but less than 180 C. to volatilize said benzene and, thereafter, said cobalt chelate; hydrolyzing said volatilized cobalt chelate in a boiling water solution having a pH of from 2 to 8 to form a volatile B-diketone-Water azeotrope and cobalt hydroxide; and reducing said cobalt hydroxide to elemental cobalt.

12. The method of claim 11 in which the chelating agent of ithe B-diketone type is substantially symmetrical and has the keto form of:

ii R-C O H Il l H C-CIJ H where: R is a hydrocarbon radical selected from the group consisting of CH3, C2H5 and CsHf, and R is a hydrocarbon radical selected from the group consisting Of CH3, C2H5 and C3H7.

13. The method of claim 11 in which the B-diketone is 2,4-pentanedione.

14. The method of isolating spectrographically nickelfree cobalt from a nickel-cobalt mixture comprising: chelating Ithe nickel-cobalt mixture with B-diketone solution; adjusting the pl-l of said solution to a -value of from 4 to 7; whereupon nickel chelate and cobalt chelate separate therefrom; removing `the chelates from said solution; heating said chelates to a temperature of at least C. Ibut not over about 190 C. to volatilize said cobalt chelate without volatilizing said nickel chelate; hydrolyzing said volatilized cobalt chelate to cobalt hydroxide; and reducing said cobalt hydroxide to elemental cobalt which, by spectrographic analysis, is free of nickel.

15. The method of claim 14 in which the B-diketone is substantially symmetrical and has the keto form of:

Where: R is a hydrocarbon radical selected from the group consisting of CH3, C21-l5 and (23H7 and R is a hydrocarbon radical selected from the group consisting Of CI-Ig, C2H5 and (23H7.

16. The method of claim 14 in which the B-diketone is 2,4-pentanedione.

17. The method of isolating spectrographically nickelfree cobalt from a nickel-cobalt solution comprising: precipitating nickel and cobalt with a B-diketone type chelating agent from solution as chelates; heating said chelate precipitate to a temperature of at least 140 C. but less than C. to volatilize the cobalt chelate Without volatilizing the nickel chelate; collecting said volatilized cobalt chelate; and reducing said cobalt chelate to elemental cobalt.

18. The method of claim 17 in which the nickel and cobalt chelates are formed by reaction with a substantially symmetrical B-diketone having the keto form of:

19. The method of claim 1S in which the B-diketone is 2,4-peutanedione.

References Cited in the le of this patent UNITED STATES PATENTS 2,722,481 Werntz Nov. 1, 1955 2,954,276 Hazen Sept. 27, 1960 2,955,932 Goren Oct. 1l, 1960 FOREIGN PATENTS 760,279 Great Britain Oct. 31, 1956 569,435 Canada Jan. 20, 1959 

1. THE METHOD OF ISOLATING SPECTROGRAPHICALLY NICKELFREE COBALT FROM A RAW SOLUTION CONTAINING NICKEL AND COBALT COMPRISING: INTRODUCING AN OPERABLE B-DIKETONE INTO SAID SOLUTION AND SUBSEQUENT THERETO, A PH ADJUSTER TO BRING THE PH OF SAID SOLUTION TO A VALUE OF FROM ABOUT 4 TO ABOUT 7 TO PRECIPITATE NICKEL AND COBALT AS COBALT AND NICKEL B-DIKETONATES; SEPARATING SAID B-DIKETONATE PRECIPITATE FROM SAID SOLUTION; REMOVING SURPLUS LIQUID FROM SAID PRECIPITATE; HEATING SAID PRECIPITATE TO A TEMPERATURE OF AT LEAST ABOUT 140*C. TO VOLATILIZE SAID COBALT B-DIKETONATE WITHOUT VOLATILIZING SAID NICKEL B- 